1. Field of the Invention
The invention pertains to a method for operating a drive train belonging to a motor vehicle, the drive train being provided with:
a torque-generating arrangement, which comprises at least one drive unit, possibly in the form of an internal combustion engine, and possibly an auxiliary unit for generating an auxiliary torque;
a gearbox (especially a power-shift gearbox) with a synchronizing device and with at least two gearbox input shafts and at least one gearbox output shaft, where a first gearbox input shaft is assigned to at least one first gear and a second gearbox input shaft is assigned to at least one second gear;
a multi-clutch device, possibly a double-clutch device, installed between the drive unit and the gearbox to transmit torque between the drive unit and the gearbox, this clutch device comprising a first clutch arrangement assigned to the first gearbox input shaft and a second clutch arrangement assigned to the second gearbox input shaft, where the two clutch arrangements can be actuated independently of each other.
2. Description of the Related Art
A method of this type is known from DE 196 31 983 C1, which corresponds to U.S. Pat. No. 5,890,392. The goal which the method disclosed in this patent document was intended to achieve was to make it possible to shift without the need for any intervention in the management (engine management) of the internal combustion engine, that is, without the need to exert any effect on its power output stage during the shifting method. The method was also intended to make it possible to operate as completely as possible without internal synchronization of the gearbox. According to this approach, it is sufficient to provide a gearbox which requires internal synchronization of the gear wheels for only certain types of shifting, whereas, for other types of shifting, the synchronization is achieved in what could be called an external manner by means of the clutch device.
The method of DE 196 31 983 C1 has the result that the torque acting on the power takeoff element is not constant during the shifting method. As a result, there can be undesirable intermediate accelerations or intermediate decelerations during the course of shifting. These make the ride less comfortable for the driver and the passengers during the shifting operation.